Up to now, semiconductor devices including a semiconductor substrate in which plural gate electrodes are juxtaposed, and plural transistor cells are included as cells defined by adjacent gate electrodes have been known. The semiconductor device has gate wirings electrically connected to the gate electrodes on a first surface of the semiconductor substrate, and the gate wirings are connected with gate pads as external connection terminals. In addition, a first pad common to the plural transistor cells is formed on the first surface of the semiconductor substrate, and a second pad common to the plural transistor cells is formed on the first surface of the semiconductor substrate, or on a second surface opposite to the first surface. For example, when a vertical IGBT is formed in each of the transistor cells, the first pad is an emitter pad, and the second pad is a collector pad formed on the second surface.
In the semiconductor device of this type, for example, in order to ensure operation at high current density, a predetermined voltage is applied between the first pad and the second pad, and a large current, for example, several hundreds A are allowed to flow therebetween to implement screening. In a conventional method of bringing the plural probes into contact with the first pad for energization, in order to increase a test current, there is no choice but to increase the number of probes, or to increase current per probe. However, when the current per probe increases, a local current concentration caused by contact variation between an inspection device and the pad is more likely to occur. In addition, when the number of probes increases, the current concentration is likely to occur due to height variation of the probe. Furthermore, an increase in the number of probes is limited by the size of the first pad.
On the contrary, in PTL 1, a semiconductor element is arranged on a support base so as to come into contact with the second pad (collector electrode), a contact is brought into contact with each gate pad (gate electrode), and a conductive resin is brought into contact with the first pad (emitter electrode). A conductor and a weighting mechanism are placed on the conductive resin, and the conductor, the conductive resin, and the semiconductor element, which are disposed below the weighting mechanism, are weighed by the weighting mechanism so that the contact area increases to suppress the current concentration.
However, the inspection device used in PTL 1 is a device and a method using the conductive resin which are special as compared with general inspection devices used for screening, and increases the costs since the throughput becomes poor.